In the Article 'Some Thoughts' published in Newsletter 40, I mentioned the idea of using camber combined with hinges to get the camber right forward in the sail, so I find it interesting that the idea is now being discussed. I must admit that I am not a fan of hinges, believing that a 'solid pole' has less to go wrong, but it would be interesting to see how the combined camber/ hinge would work in practice.
For some reason some people seem to have the idea that cambered panels are complicated and difficult to live with. I have been told that even the commercially built shelf foot sails are causing a lot of fiddling to set them up. Making enquiries about this I find that the 'professionals' do not seem to clearly understand Arne's simple cambered rig. For some reason they are rigging the sails with neither batten parrels nor Hong Kong parrels, and are trying to remove creases with multiple luff hauling parrels which need to be adjusted on a regular basis.
The simple Hasler/ Mcleod sail with cambered panels only really needs standing Hong Kong parrels to replace the diagonal stability and rigidity of the flat sail to make it behave like a simple flat sail, but with the added performance. Why make life difficult when it is really quite simple?
Incidentally, I am not 100% convinced that the shelf-foot method of building the commercial version of the cambered sail is the best way. Looking at the 3 pictures of Jonathan Snodgrass’s ‘Lexia’ in the newsletter 55 I feel there is more material hanging around than is necessary. When I told Chris Scanes that I had used a variation of a shelf-foot to make the ‘jibs’ of my split rig he rushed off and started building the sails with the simple shelf-foot as he could understand them. He didn’t listen when I explained that I had modified the shelf-foot idea and ended up with the same camber but with less material across the panel.
Chris claims that the shelf-foot is easier (do we understand ‘Cheaper’) to build than round and broadseam method I talked him through for his first successful cambered sail, but I feel that he used it because he was not happy the calculations I had done for the latter sail, and could not guarantee to reproduce them for a different sized sail. The real question when you look at Lexia’s sails is, if using the shelf foot method, should it be modified to improve the set?
Personally, I still think that if you are worried about the little wrinkles in Arne’s sail then the vertical cloths with Round and Broadseam is probably easier and quicker to build than the shelf foot when the calculations are run off on the computer.
Cheers
Slieve
PS.
Reading
the above after posting it I realise I may have given a wrong impression. The point of the posting was to encourage the readers to question and discuss if there may be a better method of making the shelf-foot sails. The reference to the photos of ‘Lexia’ were an attempt to illustrate the point and not to criticise the boat or its sails. Speaking to Jonathan before I wrote the above he told me that the photos were all taken in a flat calm, and in such conditions all cambered sails will show some excess cloth to a greater or lesser extent over a flat sail as on the Barbican 33 ‘Janvier Aquila’ in the third photo. Jonathan did confirm that when a light breeze did arrive ‘Lexia’, with her cambered sail did show the expected better performance over the flat sailed boat. There is no question in my mind that a cambered sail will outperform a flat sail, and in particular when sailing to windward. I am convinced that Jonathan was right in fitting cambered sails to 'Lexia', and will enjoy the better performance they will bring. My question is ‘can the shelf-foot sail be built with less material to do the same job?’
PS This is a straight copy of my post in the R & D forum.